1. Field of the Invention
The present invention relates to light-emitting modules, and in particular, to laser modules that are provided with a one-piece housing, and to methods for manufacturing same.
2. Description of the Prior Art
Currently-available laser modules include a laser source and a lens piece that are housed together. When manufacturing these laser modules, the lens must be focused with respect to the laser source. There are three currently-available embodiments of such laser modules.
Referring to FIGS. 1A and 1B, a first conventional laser module 20 is comprised of a lens housing 22 and a laser housing 26. The lens housing 22 houses an O-ring 23 and a lens 24 (see FIG. 1B). The laser housing 26 includes a laser source 28 permanently secured at one end thereof by glue or similar securing means. The lens housing 22 has a plurality of external threads 30 that are adapted to rotatably engage a plurality of internal threads 32 provided at the other end of the laser housing 26 opposite from the laser source 28. The laser housing 26 further includes a side opening or window 34 extending through the wall of the laser housing 26. During assembly of the laser module 20, the lens housing 22 is rotatably secured at the internal threads 32 of the laser housing 26, and the lens 24 is focused by rotating the two housings 22, 26 (about the threads 30 and 32) with respect to each other to adjust the relative distance between the lens 24 and the laser source 28.
The focusing can be accomplished by using conventional and well-known methods. For example, a laser beam is emitted from the laser source 28 through the lens 24 and directed on to a surface. The size of the dot formed on the surface is adjusted until the smallest dot size is obtained, and it is at this point that the lens 24 has been properly focused with respect to the laser source 28. This focusing method is typically done manually.
Once the lens 24 has been properly focused, glue can be introduced through the side window 34 to affix the lens housing 22 at the focused position with respect to the laser housing 26. A separator 36 is positioned between the laser source 28 and a PC board 38 to complete the assembly of the laser module 20. FIG. 1B illustrates the completed laser module 20.
FIGS. 2A and 2B illustrate a second conventional laser module 40, again having a lens housing 42 and a laser housing 44. The lens housing 42 includes a cylindrical housing 46, an O-ring or washer 48, a lens piece 50, and a connector 52. The cylindrical housing 46 receives the O-ring 48 and lens piece 50, with the connector 52 retaining the lens piece 50 securely inside the cylindrical housing 46. A front opening 53 is provided at a front end of the housing 46 to allow the laser beam to be emitted therethrough. The laser housing 44 includes a laser source 54 permanently secured at one end thereof, and a plurality of external threads 56 provided at the other end thereof that are adapted to engage a plurality of internal threads 58 provided on an inside surface of the connector 52. To assemble the laser module 40, glue is placed on the external threads 56, and the internal threads 58 of the connector 52 of lens housing 42 are rotatably secured at the external threads 56 of the laser housing 44. The lens 50 is then focused by rotating the two housings 42, 44 (about the threads 56 and 58) with respect to each other to adjust the relative distance between the lens 50 and the laser source 54. Once the lens 50 has been properly focused, the glue placed on the threads 56 is allowed to harden to affix the lens housing 42 at the focused position with respect to the laser housing 44. A separator or spacer 60 is positioned between the laser source 54 and a PC board 62 to complete the assembly of the laser module 40. The spacer 60 also functions to secure the laser source 54 at a fixed permanent position inside the laser housing 44. FIG. 2B illustrates the completed laser module 40. Thus, the difference between the laser modules 20 and 40 is that internal threads 32 are provided on the laser housing 26 for engaging external threads 30 of the lens housing 22 for laser module 20, while external threads 56 are provided on the laser housing 44 for engaging internal threads 58 of the lens housing 42 for laser module 40.
FIGS. 3A and 3B illustrate a third conventional laser module 70, again having a lens housing 72 and a cylindrical laser housing 74. The lens housing 72 includes a cylindrical housing 76, an O-ring or washer 78, a lens piece 80, and a spacer 82. The cylindrical housing 76 receives the O-ring 78 and lens piece 80, with the spacer 82 retaining the lens piece 80 securely inside the cylindrical housing 76. A front opening 83 is provided at a front end of the housing 76 to allow the laser beam to be emitted therethrough. The laser housing 74 includes a laser source 84 permanently secured at one end thereof by glue or similar means. The laser housing 74 further includes a side window 86 extending through the wall of the laser housing 74. A spring 88 is positioned inside the hollow cylindrical interior of the laser housing 74. During assembly of the laser module 70, the lens housing 72 is received inside the cylindrical laser housing 74, with the spring 88 operating to space the lens 80 apart from the laser source 84. The lens 80 is then focused by adjusting the relative distance between the lens 80 and the laser source 84, as controlled and biased by the spring 88. Once the lens 80 has been properly focused, glue can be introduced through the side window 86 to affix the lens housing 72 at the focused position with respect to the laser housing 74. Alternatively, the lens housing 72 and laser housing 74 can be welded together. FIG. 3B illustrates the completed laser module 70. Thus, the laser module 70 differs from the laser modules 20, 40 in that laser module 70 uses a spring 88 to adjust the relative distance between the lens 80 and the laser source 84, without using any threaded connections between the lens housing 72 and the laser housing 74.
Each of these conventional laser modules 20, 40, 70 provides at least two separate housings, one for the lens and one for the laser source, that must be adjusted with respect to each other to properly focus the lens. As a result, these laser modules 20, 40, 70 suffer from certain drawbacks. First, assembly of these laser modules 20, 40, 70 is usually done manually, typically by hand, so that assembly can be an expensive and labor-intensive process. In addition, manual focusing is always subject to human error. Second, the use of welding or the application of glue to affix one housing at a fixed position with respect to another housing is disadvantageous since the relative positions of the two housings can shift during welding, or as the glue settles and hardens, thereby affecting the proper focus of the lens. Third, the provision of two separate housings increases the number of components of the laser module 20, 40 or 70, thereby increasing the cost and complexity of the laser module 20, 40 or 70.
Thus, there still remains a need for an improved laser module which overcomes the drawbacks of the prior art laser modules. In particular, there remains a need for an improved laser module which provides for accurate focusing of the lens, which is less costly to manufacture, which minimizes the total number of components used in the assembly of the laser module, and which allows for mass-production of the laser module without the need for manual assembly.